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after using both systems it seems that the trick to realflows paricle system smarts is sort of advanced level interact(pop).

houdini can do all the stuff the daemons do, but realflow real strength is in the way it can make its particles aware of each other. that is what the interact could really be. I mean WOW. chof viscosity gas and temperature and internal and external pressure.

the mesh generation is metaballs .... but then it is also optimized.

but realflow's inherit weakness versus houdini is no scripted geometry render. hours of opengl cook show and tell time.

and that is what i see in 1.3 I hear 2.0 is really nice.

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you can't really approach a CFD system with particles alone (I guess). It obeys equations that take into account the state of the whole volume at any given time (hence the metaballs), and since it's a simulation, it goes trough iteration, determining the next frame based on the frame before it (well, that's true for POPs too, but it only deals on a a particle per particle basis, interact is one of the rare POPs that let them...well...interact..as far as I remember...)

particles are added later in the process (I expect..) and their motion derived from the simulation...as secondary motion, to give the result more er......"oomph" ...overlap, secondary animation, that stuff....

BTW, interact is kinda limited at doing one thing, there are other approaches that work just as well (wish I could show the R&H demo where they did the mice army for "cats and dogs", or the water drip simulation for "hollow man"...talk about lateral thinking! POPs at their best!

fluid dynamics for Shrek is also pretty cool!)

in short, our beolved app lacks the "smarts" to pull off a stunt like that (just talking about simulating the phenomenon, not reproducing it), but IMHO houdini has a darn good environment to write a simulator in, just don't expect it to do anything fancy straight out of the box in THIS department.....

(oh, and the cloth dept. either )

...

.. not yet anyways he he he

but hey!....until then it can do a darn good job faking it!

but realflow's inherit weakness versus houdini is no scripted geometry render. hours of opengl cook show and tell time

that's the nature of the beast....very computation intensive...this kind of sim was unheard of on a PC a few years ago, let alone used in the entertainment industry....

on the other hand, there are people that came up with ways (*cough* maya *cough*, and few others) to get it runnning in realtime, or at least with decent feedback time...but I'm ready to bet it's just a matter of time before we see more of that included within in all apps in the future...(hey, the sigg. paper about realtime CFD got released QUITE a while ago! what are YOU waiting for he he he ;P )

one more thought, it's been a really recurrent thread on the list, it's a tricky balance for the developers, that has to maintain:

implement new features (with potential bugs) vs. getting the app more sturdy (there are only 24h in a day, y'know, can't have both)....whaddaya think? ripe for a poll.....

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Well, considering that I am feeling a little desperate at the need for cloth and hair simulation for my current project, I'll have to go with numero uno. (Sorry, my girl CANNOT be bald.) After all, most of us can still cheat GI.

Not that I am going to attempt this, but what would one need in order to write our own simulator or a voxel renderer? A C program? HDK? Houdini's schematics?